The main work of this paper focuses on the simulation of binary alloy solidification using the phase field model and adaptive octree grids.
Ni-Cu binary alloy is used as an example in this paper to do research on the numerical simulation of isothermal solidification of binary
alloy. Firstly, the WBM model, numerical issues and adaptive octree grids have been explained. Secondary, the numerical simulation
results of three dimensional morphology of the equiaxed grain and concentration variations are given, taking the efficiency advantage of
the adaptive octree grids. The microsegregation of binary alloy has been analysed emphatically. Then, numerical simulation results of the
influence of thermo-physical parameters on the growth of the equiaxed grain are also given. At last, a simulation experiment of large scale
and long-time has been carried out. It is found that increases of initial temperature and initial concentration will make grain grow along
certain directions and adaptive octree grids can effectively be used in simulations of microstructure.
In vitro embryogenic callus is a critical factor for genetic transformation of rice, especially for indica varieties. In this study, we investigated the relationship between polyamines, including putrescine (Put), spermidine (Spd) and spermine (Spm), and callus browning, and we studied the effect of exogenous Put on callus regeneration and on the content of endogenous polyamines. In addition, the expression levels of arginine decarboxylase gene (Adcl) and S-adenosylmethionine decarboxylase gene (Samdc) in embryogenic callus were studied by quantitative Real-time PCR analysis. The results showed that the contents of endogenous Put and Spd in the browning callus were significantly lower than those in normal callus. Exogenous Put could effectively improve the growing state of callus of indica rice and enhance the development of embryogenic callus. The content of endogenous polyamines in embryogenic callus, especially Spd and Spm, was increased after addition of exogenous Put. Additionally, exogenous Put also had an obvious impact on the expression levels of Adcl but partial effect on the expression levels of Samdc gene. This study could increase the knowledge of both embryogenic callus induction and polyamine catabolism in callus in indica rice.